写一个string双向链表模块，具有提取和插入功能。通过建立一个程序语言种类的表来练习这个模块。为这个表提供一个sort()函数。并提供一个函数反转表中字符串的顺序。
环境：vs2005 win32控制台程序
#include <iostream>
#include <assert.h>
#include <string>
#include <algorithm> // for std::swap
using std::string;namespace StringList
{
// using std::string;struct Node
{
string string_;
Node *prev_;
Node *next_;
} head_node, tail_node; // Start node and End nodetypedef Node *Cursor; // Cursor like a iterator
void init()
{
head_node.prev_ = tail_node.next_ = 0;
head_node.next_ = &tail_node;
tail_node.prev_ = &head_node;
}inline Cursor next(Cursor c)
{
assert(c);
return c->next_;
}inline Cursor prev(Cursor c)
{
assert(c);
return c->prev_;
}inline Cursor head() { return &head_node; }
inline Cursor tail() { return &tail_node; }string extract(Cursor c)
{
assert(c != head() && c != tail());
string s = c->string_;
c->prev_->next_ = c->next_;
c->next_->prev_ = c->prev_;
delete c;
return s;
}Cursor insert_after(Cursor c, string s)
{
assert(c != tail());
Node *n = new Node;
n->string_ = s;
n->prev_ = c; // Before n
n->next_ = c->next_; // After n
c->next_ = n; // After c;
n->next_->prev_ = n; // Before n->next_
return n;
}Cursor insert_before(Cursor c, string s)
{
assert(c != head());
Node *n = new Node;
n->string_ = s;
n->prev_ = c->prev_;
n->next_ = c;
c->prev_ = n;
n->prev_->next_ = n;
return n;
}void reverse()
{
// First exchange the prev_ and next_ pointers
// inside each internal node:
for (Cursor c = next(head()); c!=tail(); c = c->prev_)
std::swap(c->prev_, c->next_);// Then exchange the head and tail positions:
tail()->prev_->prev_ = head();
head()->next_->next_ = tail();std::swap(head()->next_, tail()->prev_);
}namespace // unnamed namespace
{
void quicksort(Cursor left, Cursor right)
{
Cursor p = left->next_;
Cursor l = left->next_, r = right->prev_;if (left == right || l == right || l == r) return;
while (true)
{
while (l != r && l->string_ < p->string_)
l = next(l);
while (l != r && p->string_ <= r->string_)
r = prev(r);
if (l == r)
break;
std::swap(l->string_, r->string_);
}if (l->string_ < p->string_)
{
if (r->next_ != right) l = next(l);
}
else
{
if (left->next_ != r) r = prev(r);
}quicksort(left, l);
quicksort(r, right);
}
} // End unnamed namespacevoid sort()
{
if (head()->next_ != tail() && head()->next_->next_ != tail())
quicksort(head(), tail());
}
} // End namespace StringListvoid print_stringlist()
{
StringList::Cursor p = StringList::head();
while ((p = StringList::next(p)) != StringList::tail())
std::cout << p->string_ << std::endl;
}int main()
{
StringList::init();
StringList::insert_before(StringList::tail(), string("Cobol"));
StringList::insert_before(StringList::tail(), string("Fortran"));
StringList::insert_before(StringList::tail(), string("Lisp"));
StringList::insert_before(StringList::tail(), string("Algol 68"));
StringList::insert_before(StringList::tail(), string("Basic"));
StringList::insert_before(StringList::tail(), string("Pascal"));
StringList::insert_before(StringList::tail(), string("C"));
StringList::insert_before(StringList::tail(), string("Ada"));
StringList::insert_before(StringList::tail(), string("Modula-2"));
StringList::insert_before(StringList::tail(), string("C++"));
std::cout << ">>> Original list of strings: \n";
print_stringlist();
std::cout << "\n>>> Reversed list of strings: \n";
StringList::reverse();
print_stringlist();
std::cout << "\n>>> Sorted list of strings: \n";
StringList::sort();
print_stringlist();
std::cout << "\n>>> Done.\n";return 0;
}
string双向链表